PROJECT IV ? IMPACT OF NOCTURNAL BLOOD PRESSURE ON CARDIAC STRUCTURE AND FUNCTION IN OBESITY PROJECT SUMMARY/ABSTRACT The proposed project will compare the tolerability and utility of measuring blood pressure (BP) during sleep (i.e., nocturnal BP) using home BP monitoring (HBPM) versus ambulatory BP monitoring (ABPM) to assess their importance as risk factors for cardiac hypertrophy and diastolic dysfunction in a biracial U.S population. We will also identify the impact of nocturnal BP by HBPM and ABPM on cardiac structure and function in obese compared to non-obese individuals. Finally, we will elucidate potential mechanisms linking adiposity to high nocturnal BP. We will quantify site-specific abdominal fat, including visceral adiposity, renal sinus fat, and perirenal fat, and assess their associations with nocturnal BP. We will recruit a study sample of white and black adults (n=125) with hypertension aged 18-50 years who receive medical care at the University of Mississippi Medical Center. Within this sample, 50% of the study participants will have body mass index (BMI) ?30kg/m2, 25% will have BMI ?25 and <30kg/m2, and 25% will have BMI <25kg/m2. We will measure: (1) home BP in the morning and evening for 7 consecutive days; (2) nocturnal home BP for 7 consecutive nights; and (3) ABPM for one 24-hour period. Participants will undergo HBPM and ABPM in a random order. Participants will also undergo echocardiography for assessment of cardiac function and remodeling and abdominal MRI to quantify specific abdominal fat depots. The proposed work will provide key data to improve assessment of BP-related cardiovascular disease (CVD) risk, identify specific fat depots that contribute to increased nocturnal BP and CVD risk, identify new targets for therapeutic interventions for preventing cardiac remodeling and heart failure, and improve health outcomes for obese individuals.